Evaporators for household refrigerators



June 11, 1957 w. B. HERNDON, JR

EVAPORATORS FOR HOUSEHOLD REFRIGERATORS 4 Shets-Sheet 1 Filed May 23, 1955 INVENTOR.

June 11, 1957 w. B. HERNDON, JR

EVAPORATORS FOR HOUSEHOLD REFRIGERATORS 4 Sheets-Sheet 2 Filed May 23, 1955 June 11, 1957 w. B. HERNDON, JR

EVAPORATORS FOR HOUSEHOLD REFRIGERATORS 4 Sheets-Sheet 5 Filed May 23, 1955 June 11, 1957 w. B. HERNDON, JR 2,795,116

EVAPORATORS FOR HOUSEHOLD REFRIGERATORS 4 Sheets-Sheet 4 Filed May 25, 1955 I v llllll llk I INVENTOR.

United States Patent EVAPORATORS ron HOUSEHOLD REFRIGERATORS William B. Herndon, mesne assignments, a corporation of Delaware Application May 23, 1955, Serial No. 510,171 3 Claims. (Cl. 62-103) In, Evansville, Ind., assignor by The present invention relates to evaporators for household refrigerators, and is particularly concerned with evaporators which are adapted to be provided with automatic defrosting arrangements.

One of the objects of the invention is the provision of an improved evaporator construction which is simple,

which has a minimum number of parts and which may be manufactured at a low cost.

Another object of the inventionis the provisionof an improved evaporator construction in which the refrigerrefrigeration system with refrigerant which is absorbed in the oil, and which permits the use of a generous charge of such refrigerant, so that an ample supply of refrigerant is available at low ambient temperatures, when the refrigerant absorption in the oil is at a maximum.

Another object of the invention is the provision of an improved evaporator adapted to provide 'a freezing compartment inside the evaporator, and in which the cooling coils are all located on the outside, the evaporator also serving to cool the food storage space which is used inside the refrigerator for storing food at a temperature above freezing;

Another object of the invention is the provision of an improved evaporator construction adapted to eliminate the danger of frost blisters which occur during successive freezing and thawing operations, when voids formed in the brazing material fill with water and bring about a coil leak due to the expansion of the water at the joint between the tube and the sheet metal housing of the evaporator.

Another object of the invention is the provision of an improved evaporator construction for minimizing the trapping of water on the evaporator top between the transversely extending coils and at the top oftheevaporator.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the four sheets of drawings accompanying the specification, v

Fig. 1 is a fragmentary front elevational view of a household refrigerator equipped with an evaporator embodying the invention;

Fig. 2 is a view in perspective showing the top and rear of the evaporator;

to Whirlpool-Seeger Corporation,

the invention is the provision of an be used in a high side "ice Fig. 3 is a view in perspective showing the arrangements of the freezing coils;

- Fig. 4 is a front Fig. 5 is a top plan view of the evaporator;

Fig. 6 is a side elevational view taken side of Fig. 4;

Fig. 7 is a fragmentary end elevational view of the arrangements for clamping an electric heater to the rearmost pass of tubing on the bottom of the evaporator;

Referring to Fig. 1, 10 indicates a household refrigerator, the cabinet of which is'provided with an outer shell 11, and an inner-liner 12, and with a suitable door (not shown).

The outer shell 11 has an inwardly turned face flange 13, for engagement by the door, and the space between the shell 11 and the liner 12 is filled with insulation and covered at the front by an insulating breaker strip 14.

15 indicates an improved evaporator embodying the invention, which is supported on the inside of the liner 12 from the top wall 16 of the liner by means of a plurality of supporting brackets 17, 17, at the back, and 18, 18, at the front.

The evaporator 15 is preferably spaced from the top of the liner by means of the upper space 19, and is preferably wide enough to substantially fill the upper portion of the liner 12, while leaving the side spaces 20, 20, for circulation of air about the outside of the evaporator. The evaporator is also spaced from the back wall of the liner and from the door.

The side walls of the liner 12 are preferably provided with suitable molded plastic guides 21, extending from front to back on each side wall and having the upper and lower inwardly extending guide flanges 22, 23, for slid-- ably supporting a molded insulating metal or plastic container 24, which may be provided with a cover 25, if desired, and also serves as an air bafiie, separating the lower food storage space 26 from the space around the evaporator. g

The guides 21 have air. passages 27 extending through them from top to bottom for permitting the air circulation upward on both sides of the liner; and the container 24 is spaced from the back wall and door to permit the circulation of cooled air downward at the frontand back ofthe space in the liner 12.

The evaporator 15 preferably includesa housing of thin sheet metal, such as aluminum, which is provided with a top wall 28, bottom wall 29, right side wall 30, and left side wall 31, these walls being joined by easy bends 32 at each of the corners. I

The evaporator housing is preferably made of a single sheet of rectangular shape which is bent at the four corners 32, and has its end edges 33 brought into abutting relation on the left side of the evaporator, Fig. 1, where they may be secured by welding or suitable securing means.

At its rear edge the evaporator around all four sides with housing is provided an outwardly extending integral flange 34, and at its front edge it is provided with a similar and providing its bottom 29 w1th a ledge at the opening for retaining ice trays and food inside the evaporator.

The top 28 of the evaporator preferably has a pair of front to rear inwardly extending pressed ribs 40, 40, thus providing a front to rear trough 41 on the outside of the top and passing beneath the refrigerant coils, which are from the right spaced from the top at the two troughs 41,- drainage of condensate from the spaces between erant coils on the top.

The evaporator housing is preferably closed at the back by means of minum cover, with stamped ribs 44 for stiffening it:

Rear cover 42 has-a forwardly extending border flange 45 on all of the four sides of the evaporator, this flange being joined to the back wall 43 -by easy bends at 46 The size and shape ofthe rear cover 42 issuch that its insidewalls register with the inside walls of theevaporator housing, and the rear cover hasan outwardly extending border flange 47'on all four sides whichhasa"u b*end48 atits edgeandisbent over and clampedon the rear flange the refrig- 34 of the evaporator housing by an inwardly extending portion 49; all of these parts being -ofsheetaluminium Theevaporator'isprmdded with'a suitablepivoted in sulatingfront door (not'shown). Onits"'back wall the evaporator-is providedwith'a header or receiver 50', comprising an enlarged'tubular aluminum member;'tlie ends to 'the evaporator tubing."

The header 50 extends diagonally across thereai' wall 43 of rear cover42 onth'e outside, where it is secured by a sheetmetal clamping strip 55,havin'g a'cylindricalpor tion 56, extendingabout'the header, and two attaching flanges 57 secured to the rear wall 43 by rivets 581 Thusthe'header 50 extendsfro'm the lowerpart ofthe evaporator almost to the top but is below the upper coils and above the lower coils.

By extending header 50diagonally its capacity is increased by the increased length permitted, anda generous supply of refrigerant may becontained in the header, the level of which is not chan l the evaporator changed if the header were vertical.

' The present evaporator is to be used with a high side refrigeration system, in which the refrigerant is Freon (F-l2), and the header 50 is to be provided with a charge of refrigerant extending well 'upinto the header but spaced from" its upper outlet 59.

60 indicates the suction tube outlet of the evaporator, which leads to the compressor inlet, and is connected at 59 to the header 50 inside the cylindrical end opening. 53.1

At itslower end the header refrigerant outlet 61 to the aluminum tube 62, which ex; tends laterally across the right wall to the bottom coils 64, which are sinuously arranged on the outside of the bottom wall 29 of the evaporator, forming a trap at 63. I

The bottom sinuous coils 64 are seen in dotted lines in Fig; 5, where there is a forward pass 65 of the-bottom tubing, a front transverse pass 66, and additional transverse passes 67 70', inclusive, joined successively by the U-bends' 71-74 and ending on thebottom at the right end 75 of the rear pass 70.

At 75 the evaporator tubing extending from the bottom wall is bent'upwardly, having an upwardly extending por tion' 76 and a sloping portion 77, joined to a U-bend 78; and a second sloping portion 79, joined to U-bend 80; and a third sloping portion 81. This leads to an upwardly extending portion 82, all of the foregoing tubing 76-82 being located on the rightside wall 30 on the outside to which the tubing is secured, as further described.

At the. upper right corner the tubing is bent laterallyat 83, and extends transversely at 84, across the top 28 of the evaporator on the outside, the top coils being indicated by the numeral 85.

These top coils are arranged 'sinuously and include alsothe transverse passes'86-t90, which are joined to thefront pass 84 and to eachother successively by the U-bends 91-95.

The rearmost upper pass 90.is.bent .rearwardlyaat 96 and has a rearwardly extending portion 97, and a down permittingwardly extending portion 98, which extends into and communicates with the top of the header 50 at a header inlet 99, Fig. 4.

Thus the header is connected to the evaporator coils or tubing at both ends of the tubing, and the tubing consists of one continuous length or run of tubing, suitably bent and formed on a jig and then applied to the evaporator to which it is secured as follows:

Ordinary cylindrical tubing is employed wherever it is not to be welded or brazed to the sheet aluminum housing, but wherever the tubing is to be so secured, the tubing is provided with a radially extending integral rib 100, Fig. 6, having a plane edge surface 101 which is brought into engagement with the sheet metal wall and brazed or welded to said sheetmetal wall.

This may be accomplished while the evaporator shell is flat by arranging wires of brazing or welding material, provided with flux, along each ofthe joints at the edge surface 101, and then subjecting the entire evaporator to sufiicientheat to melt the brazing, soldering or welding material, and causing it to fill by capillary attraction the crack between the tubing at 101 and the sheet metal, where the melted metal tends to form an integral connection with a fillet on both sides, securing the tubing throughout at the rib 100. The evaporator is then formed by bending the sheet with tubes attached, and welding the overlapping ends.

This spaces the tubing from the sheet metal and eliminates'any possibility of the expansion of the point by ice contained in voids which might cause a leak in the tubing, if the tubing had no such rib; but the rib spaces any such voids and breaks from the tubing The'inlet from the condenser and capillary restrictor ofthe system to the evaporator is by means of the tube 102,,Fig. 6, which extends into the bottom tubing at 103 between the third and fourth lower passes on the right inaFig.v 5.

An electric heater 104 of the type having a metal housing .of tubular shape surrounding a refractory which contains the resistance heater wires is preferably clamped to the lower rear pass 70, by means of the clamping members 105 and 106.

Clamping member 105 comprises an elongated sheet metal member formed along one edge with the curved cylindrical flange 107, that engages the outside of the tube 70, oppositeto the heater 104.

This clamping member has a horizontally extending portion108, which traverses tube 70 and heaterv 104, and is bent downwardly at 109. It has an integral securing flange with a plurality of holes for screw bolts 111, and a laterally turned end portion 112 that engages the clamping member 106.

The clamping member portion 113, which is joined to the vertical having the holes 115 for the bolts 111.

The curved portion 113 of clamping member 106 extends over the top of heater 104, where it is provided with an enlargement or shoe 116, the inside of which has the cylindrical surface 117, engaging about the heater 104, and making good heat transmission contact with the heater.

At its left end, Fig. 7, the shoe 116 has a cylindrical groove 118 engaging the right side of the tube 70, for good heat transmission contact.

The end parts"119 of the two clamps 105, 106, are spaced to provide roomfor 'the'rib 100 on the tube.

The bolt 111,-with its nut 120draws the clamps 105, 106, together and clamps the heater 104 tightly on the tube 70, so that this rear pass may be heated throughout its length to effect defrosting.

The course of the refrigerant may be seen by reference to Fig. 3, where the refrigerant enters through tube 102, connectedto the bottom coils 64 at 103. Here the refrigerant, which is mostly liquid may pass throughthe sinuous coils to the header as follows:

106 has a partially cylindrical portion 114,

The path from the inlet 103 is baclcwardly through passes 69 and 70 to the upwardly extending portion 76, which is connected to the side' coils 7 7-82, the refrigerant passing upward on the side wall to the top coils 85, at the point 83.

The refrigerant passes through the sinuous top coils 85, across the top of the evaporator to the rear, where it is connected to an upper part of theheader at.

The other path through passes 68,67,66, 65 to bottom of header 50, permits flow of refrigerant in the other direction, under the head of liquid in the header, aided by trap 63, which prevents reverse flow.

The liquid in the header drains into the tubing on the bottom of the evaporator and continues to circulate due to the liquid head in the header.

The volume of the header 50 is such that it holds a large supply of refrigerant and consequently there is a generous supply available at low ambient temperatures when the refrigerant absorption in the oil sump of the compressor motor is at a maximum.

When defrosting is to be accomplished the compressor motor is disconnected and the electric heater 104 is energized. This heats the refrigerant in the rear pass 70, which is one of the lowermost refrigerant passes, and the vapor and warm refrigerant circulates up the right side throughout the coils 77 to 82 and through the top refrigerant passes 85 to the top of the header 50 at 99.

At the same time liquid refrigerant is drained from the bottom of the header at 61, passing through the lower passes 66-69 to the heated pass 70 to be reheated, and this circulation is facilitated by the weight of the head of liquid in the header 50, acting against the vapor in the upwardly extending passes 7 7--82, the vapor being lighter.

Thus by heating the lowermost refrigerant pass 70, the refrigerant is caused to circulate throughout all of the tubing of the evaporator, and the refrigerant gives up its heat to the evaporator, which melts all the frost from the evaporator in a short time, before the contents of the evaporator have had a chance to become warm.

It will thus be observed that I have invented an improved evaporator for household refrigerators which includes a minimum number of parts, which is simple in construction, and rigid although constructed of thin aluminum sheet.

The evaporator tubing comprises a single, continuous length of tubing sinuously arranged on the top and bottom and one side of the evaporator and connected at both of its ends to a header containing a generous supply of refrigerant.

The evaporator may include an electric heater, heating one of the lowermost passes of the tubing and causing the heated refrigerant to circulate throughout all of the tubing while being reheated during its passage through the heated pass.

Thus it may be used either as an automatic defrost evaporator with the heater or as a non-defrost evaporator without heater.

The tubing being spaced from the sheet metal by its integral rib, which is welded to the sheet metal housing, there are no welds close to the cylindrical side wall of the tubing, where they might have voids that would cause leaks in the tubing when the contained wall becomes ice and expands.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, new and desire to secure by Letters Patent States, is:

1. In a household refrigerator, the combination of an insulated cabinet provided with an outer shell and an what I claim as of the United carried by the liner inner liner separated by insulation, said liner forming a food storage space, and an evaporator carried by said liner and comprising a box-like sheet metal member provided with a rear cover, said evaporator being provided on its outside with one continuous length of tubing sinuously arranged on the bottom, one side, and top of said evaporator, a tubular header of enlarged cross section carried by the rear wall of said evaporator and extending diagonally from one lower corner to the diagonally opposite upper corner, the said header being connected to said tubing at the bottom of the header and being connected to the tubing also at a point adjacent the top of the header, the said header having an upper suction outlet and the said tubing having an inlet on the lower tubing of said evaporator, the said evaporator being spaced from the liner on its top and both the ends and the rear and front for circulation of air, a pair of guides carried by the liner walls below the evaporator and having ventilation apertures for circulation through the guides, and a food container slida bly mounted on said guides and comprising a molded plastic insulating member separating the space in the liner into upper and lower compartments, the lower compartment being cooled by circulation of air by convection currents.

2. In a household refrigerator, the combination of an insulated cabinet provided with an outer shell and an inner liner separated by insulation, said liner forming a food storage space, and an evaporator carried by said liner and comprising a box-like sheet metal member provided with a rearv cover, said evaporator being provided on its outside with one continuous length of tubing sinu ously arranged on the bottom, one side, and top of said evaporator, a tubular header of enlarged cross section carried by the rear wall of said evaporator and extending diagonally from one lower corner to the diagonally opposite upper corner, the said header being connected to said tubing at the bottom of the header and being connected to the tubing also at a point adjacent the top of the header, the said header having an upper suction outlet, and the said tubing having an inlet on the lower tubing of said evaporator, the said evaporator being spaced from the liner on its top and both the ends and the rear and front for circulation of air, a pair of guides walls below the evaporator, and having ventilation apertures for circulation through the guides, and a food container slidably mounted on said guides, and comprising a molded plastic insulating member separating the space in the liner into upper and lower compartments, the lower compartment being cooled by circulation of air by convection currents, said container having a greater width than said evaporator and serving as a drip tray, receiving condensate from the bottom of said evaporator.

3. In a household refrigerator, the insulated cabinet provided with an outer shell and an inner liner separated by insulation, said liner forming a food storage space, and an evaporator carried by said liner and comprising a box-like sheet metal member provided with a rear cover, said evaporator being provided on its outside with one continuous length of tubing sinuously arranged on the bottom, one side, and top of said evaporator, a tubular header of enlarged cross section carried by the rear wall of said evaporator and extending diagonally from one lower corner to the diagonally opposite upper corner, the said header being connected to said tubing at the bottom of the header and being connected to the tubing also at a point adjacent the top of the header, the said header having an upper suction outlet and the said tubing having an inlet on the lower tubing of said evaporator, the said evaporator being spaced from the liner on its top and both the ends and the rear and front for circulation of air, a pair of guides carried by the liner walls below the evaporator and having ventilacombination of an 

